Patent Literature 1 discloses a refrigeration cycle for a vehicle having a gas injection cycle. The refrigeration cycle uses a compressor that compresses refrigerant using driving power generated by an engine.
However, electric vehicles such as battery vehicles and hybrid vehicles prevail in recent years, and thereby an electric compressor operated by an electric motor is used for a vehicle air conditioner mounted in a vehicle. For example, in a hybrid vehicle, the air conditioner can be operated even when an engine is stopped by using the electric compressor.